Comparison of Cigarette Smoke Exposure Atmospheres in Different Exposure and Puffing Modes

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Abstract
Mainstream cigarette smoke generated using different puffing profiles and delivered under different exposure modes was characterized for particle size distribution, vaporlgas concentration, and chemical composition. Three exposure modes were compared: (1) nose-only, intermittent (NO-I), which simulated a periodic exposure; (2) nose-only, continuous (NO-C), in which a constant smoke concentration was maintained for several hours; and (3) whole-body, continuous (WB-C), which was similar to the NO-C mode except that the smoke was routed to a whole-body instead of to a nose-only exposure chamber. Three different puffing profiles were compared: (1) a standard (SP), 2-s, 35-ml puff once per minute; (2) a puff of double the standard volume (70 ml) once per minute (OP); and (3) a double puff twice per minute (2-DP). Results from multijet Mercer impactor samples indicated that the mass median aerodynamic diameter of smoke particles increased with mass concentration and decreased with puff volume. Gas samples showed no substantive differences between exposure modes with or without rats in the exposure chambers, except for CO2 concentrations in the WE-C chambers, NO2 concentrations in the NO-I chambers, and NO concentrations in the NO-C chambers. Linear relationships were observed between the concentration of total particulate matter and that of CO, NO, and volatile organic hydrocarbons under all exposure and puffing modes. Concentrations of six different organic vapors (acetone, 2-methylfuran, benzene, meta- and para-xylene, ortho-xylene, and limonene) were measured using Tenax trapping technique. The results showed no substantive differences among the three exposure modes or three puffing profiles, except that the concentrations of toluene, orthoxylene, and limonene were higher in smoke from the WE-C than from the NO-C (or NO-I) modes. The amounts of four particulate-phase constituents (nicotine, glycerol, hydroquinone, and palmitic acid) were analyzed chemically; good agreement was found in the amounts resulting from all of the puffing profiles and most of the exposure modes, except that nicotine was found to be slightly lower in the WE-C mode than in the other exposure modes. Sampling results indicated that there were few substantive differences in smoke composition among the different exposure and puffing modes used in this study We concluded that WB-C exposures to the cigarette smoke generated under 2-DP profiles might produce biological effects similar to those produced under SP profiles by nose-only exposures, and might be useful for chronic animal exposures.